Every X-Rite spectrophotometer produces two levels of colour data: the familiar L\*a\*b\* values and Delta E numbers that appear on the instrument display, and the underlying spectral reflectance data from which those values are calculated. Most production teams work with the L\*a\*b\* layer — the ready-to-use colour quality data that tells them whether a colour passes or fails. But the spectral data underneath is far richer and more powerful, and understanding how to use it unlocks a range of capabilities that simply cannot be achieved with tristimulus measurements alone.
A spectral reflectance curve is the most complete physical description of a colour that measurement science can provide. It describes how a surface reflects light at every wavelength across the visible spectrum — not a single colour impression, but a full fingerprint of the surface's optical behaviour. This spectral fingerprint contains all the information needed to calculate how the colour will appear under any light source, to detect metamerism, to convert between different colour space representations, and to predict how the colour will look on different substrates. None of these capabilities are available from a simple L\*a\*b\* reading.
Illuminant-Independent Colour Description
The most immediate practical value of spectral data is illuminant independence. An L\*a\*b\* measurement is always calculated under a specific illuminant — typically D50 for graphic arts and packaging, or D65 for other industries. Two colours that have the same L\*a\*b\* values under D50 are defined as a match under D50 lighting. But they may have very different spectral curves, meaning they will have different L\*a\*b\* values under a different illuminant — a metameric pair that appears identical in D50 daylight but obviously different in A-illuminant incandescent lighting.
Spectral data reveals this immediately. If two samples have different spectral reflectance curves, the measurement system can calculate their L\*a\*b\* values and colour differences under any illuminant in its database — D50, D65, A, F2, F7, and many others — from a single measurement. This multi-illuminant analysis is invaluable in packaging colour management, where products must look consistent under the full range of retail, home, and office lighting environments they will be viewed in. The benchtop spectrophotometers in X-Rite's range provide full spectral data with multi-illuminant analysis for exactly this type of colour formulation and quality verification work.
Substrate-Specific Colour Standards
Spectral data enables something that L\*a\*b\* values cannot: the calculation of substrate-specific colour targets. A brand colour defined in L\*a\*b\* terms assumes a specific substrate and production process. The same brand colour on a different substrate — say, natural kraft paper instead of white coated board — will require a completely different L\*a\*b\* target to achieve the same visual appearance, because the underlying substrate colour changes what the ink needs to do.
Spectral data allows colour scientists to model this relationship — to take a brand's colour standard, combine it with the spectral characteristics of a new substrate, and calculate what L\*a\*b\* target the ink or coating needs to achieve on that substrate to produce the desired visual result. This capability is central to how platforms like PantoneLIVE work: storing spectral-level colour standards that can be used to generate substrate-specific targets for any production process and material combination. The eXact 2 spectrophotometer supports this workflow with full spectral measurement capability and connectivity to digital colour standard platforms.
Colour Formulation and Matching
In colour formulation — the process of mixing pigments or dyes to achieve a target colour — spectral data is far more useful than L\*a\*b\* values for guiding the formulation process. Formulation software works with spectral data to model how different pigment mixtures will combine to produce a target spectrum. The software predicts the proportions of each pigment needed to achieve the target spectral reflectance, taking into account the individual spectral absorption and scattering characteristics of each pigment component. This spectral-level modelling produces first-pass match predictions that are far more accurate than any visual estimation, and corrections that are targeted and efficient.
In plastics colour formulation, where achieving a consistent colour across different polymer types and processing conditions is particularly challenging, spectral-level formulation with X-Rite spectrophotometers significantly reduces the number of formulation iterations needed to achieve a passing result. The result is less waste, faster batch turnaround, and more reliable consistency between formulations produced at different times or locations.
Sharing Colour Data Digitally
Spectral data is also the ideal format for sharing colour standards digitally between organisations. A spectral file can be emailed, uploaded to a shared platform, or transmitted through an API — providing the recipient with everything they need to verify colour against the standard, regardless of the substrate or process they are working with. Physical samples decay and vary; spectral data is permanent and exact. For supply chain colour management at scale, spectral data sharing is the foundation of a digital colour workflow that eliminates the variability and logistics overhead of physical sample exchange.
Conclusion
Spectral data is the most powerful output of an X-Rite spectrophotometer — a complete, illuminant-independent, substrate-versatile, digitally shareable description of colour that enables capabilities impossible with tristimulus measurements alone. For businesses managing colour across complex supply chains, multiple substrates, or demanding brand standards, working at the spectral level is the path from adequate colour management to truly professional colour control. X-Rite instruments capture this data by default; using it systematically is the key to unlocking its full value.